Die-head of screwing-machines.



T. & T. P. GHATWIN & J. VIRTUE.V

DIE HEAD 0F SGREWING MACHINES. APPJJOA'HON FILED MAB. 23,`1910.

996,311. Patenteagunezv, 1911.

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DIE HEAD or SCREWING'MAGHINBS.

APPLIUATION FILED MAR. 23. 1910.

Patented June 27, 1911.

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4 SHEETS-SH ma; T.A P. CHATWIN & J. VIRTUEL DIE HEAD OP SGEBWINGMACHINES. APPLICATION FILED MAB. 23, 1910.

996,81 1 Patented June 2'?, 1911.

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T. & T. P. CHATWIN '&`J. VIRTUE.

DIE HEAD 0F SGREWING MAGHINES.

APPLICATION FILED MAB. 23` 1910.

Patented June 2'?, 1911.

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THOMAS CI-IATWIN, THOMAS PHILIP CI-IATWIN, AND JAMES VIRTUE, 0FBIRMINGHAM, ENGLAND.

DIE-HEAD 0F SCREWINGr-MACHINES.

Specification of Letters Patent.

Application filed March 23, 1910.

Patented June 27, 1911. Serial No. 551,154.

To all whom it may concern:

Be it known that we, THOMAS CHA'rWIN, engineers-tool manufacturer, andTHOMAS PHILIP CHATWIN, engineer, citizens of Great Britain, andresidents of Great Tindal street, Birmingham, in the county of Warwick,England, and JAMES VIRTUE, citizen of Great Britain, and resident of 253Maryvale road, Bournville, Birmingham, county of lVarwick, England,draftsman, have invented certain new and useful Improvements in andRelating to Die-Heads of Screwing-Machines, of which the following is aspecification. I

This invention comprises improvements m and relating to die heads ofscrewing machines, and has for its object the provision of an improveddevice for releasing the dies in such heads without stopping themachine.

The invention consists in the application of a spring so mounted as tocause the cam controlling the dies to over-run the spindle and die headto a degree limited by adjustable devices to close the dies onto thework in conjunction with a brake for retarding the cam so that thespindle and die head can overtake it, thus causing the dies to run outofl3 the work, when desired, without stopping the machine.

We are aware that a spring has been used for rotating a cam ring when acontrol device worked by contact with the work has been released for thepurpose of ope-ning dies of screwing machines and also that a brake hasbeen used in conjunction with aJ spring but in this prior case the brakewas applied to compress the spring and'close the dies so that the camring could be locked in this position by a pawl. When the pawl wasreleased the spring expanded to open the dies. In our invention we areparticularly desirous of avoiding such use of spring for opening thedies as it is found in practice not to be dependable.

On the appended drawings Figure l is a central vertical section througha die head of a screwing machine with the invention applied. Fig. 2. isa transverse section on line 2--2 of Fig. 1. Fig. 8. is a transversesection taken on line 3-3 of Fig. 1 in direction of the arrow a. Fig. 4tis a similar section on line 3--3 but looking in the direction of arrowb. Fig. 5 is a sectional view showing a brake actuating device. Fig. 6.shows one method of automatically operating the actuating device. Fig.7. is a view looking toward the back of the die head showing a catchthat may be used. Fig. 8 is a plan thereof. Fig. 9 is a. perspectiveview of al form of brake band used in the device of our invent-ion.

These drawings show, a method of carrying the invention into practice asapplied to a screwing machine having a die setting and releasing cam andchaser type dies. In this case we provide the back of the die head Awith a coned or stepped slot al concentric with the axis thereof andextending through about 120 to 140 degrees of the circle of the head,and we arrange a sliding block B in this slot provided with two lockingpins b1 b2 so that the block may be set fast at any desired position inthe slot. The adjusting and releasing cam C which is of the well knownscroll form having four eccentric die engaging faces c1 givingvariations in the closing or opening of the dies D we provide with anannular recess c2 in the side toward the back of the die head andA intothis recess projects a portion b3 of the locking pin b2 previouslymentioned which portion project-s beyond the head of the pin.

The sliding block B has within it a concentric slot b4 or recess and theearn C is equipped with a pin or peg c3 passing through the annularrecess c2 in the back into this slot b4 in the sliding block of the diehead see Fig. t. A suitable spring E is arranged in the recess c2 in thecam, one end c1 engaging the projection b3 on the locking pin b2 and theother e2 engaging the pin c3 on the cam C so that a tension is set upbetween the cam and the adjustable block and as the latter is set fastto the die head the screwing spindle also. As the cam pin 03 is free inthe slot b4 in the sliding block B this spring E keeps the pin c3 in theend of the slot farthest removed from the locking pin b2 to theprojection b3 of which the other end c1 of the spring is connected. Thisposition for the cam corresponds to the closed position for the dies,but it is obviously adjustable to suit requirements owing to thearrangement for the alteration of the position of the sliding block toallow for any adjustment of the dies within the capacity of the scrollsof the cam. It will thus be seen that, due to the slot b4 in the slidingblock B engaged by the cam pin c3 the cam C is free to rotate quiteindependently of the die head A and in a contrary direction, for adistance equal to the length of the slot in the block, but this rotationopposes the tension of the spring E and immediately the force effectingit is removed, the cam rotates forward again to the original positionwith its pin at the end of the slot as above stated. This rotation ofthe cam C contrary to the die head and against the tendency of itsspring isvreally simply relative movement between the two caused byretarding the cam and thus allowing the die head to overtake it. This iseffected by a brake applied to the cam during its rotation with the diehead and spindle, causing it to lose speed with respectto the latter sothat the die head passes it and puts the spring E in greater tension.This relative partial back rotation of the cam in respect to the spindleruns the dies D back up the scrolls c1 of the cam C and so oif the workthey are screwing. When the dies are required in screwing positionagain, the retarding infiuence or brake is removed from the cam C andits spring E forces it to overrun the spindle and die head A for thelength of the slot b4 of the sliding block B thus closing the dies D bythe action of its scrolls 01. As will be seen both these actions arecarried out without stopping the machine.

The form of brake may be suited to circumstances but we here show a bandbrake F encircling the cam C and having lugs at each end; one f1 restson a fixed step f2 and the other f3 is operated by a screw pin f4 totighten the brake around the periphery of the cam C.

A further arrangement for applying the brake F is shown at Fig. 5, whichis more readily accessible for operation and more rapid in its actionthan the previous arrangement. In this case a bearing G is secured tothe bed and has a short rod g1 working in it. The rod g1 has a thread atg2 passing through a fixed nut g3 and at its eXtremity g4 engages thelug f3 of the brake around the cam. An offset g5 forms a hand part forrotating the rod which by coaction of its thread g2 with nut g8,reciprocates in the bearing G and applies the desired force t-o lug f3of the brake. With this arrangement an automatic operation of the brake,and consequently of the dies, can readily be obtained. In such a casethe rod g1 carries a pinion g and the bearing G is provided with apassage way for a rod I-I provided with a rack 71,1, see Fig. 6. The rodII has a spring if bearing against the bearing G and a collar 7b3 at theother end has a notched portion 7b4 engaged by'a pivoted gravity orspring catch h5. The rod J projects from the machine saddle and worksthrough the guide gi in the bearing G carrying tappets j1 and jg. l

As shown at Fig. 6 the tappet j2 is just striking the end of catch h5 torelease the rod I-I which by action of its spring h2 moves fartherthrough bearing G, its rack h1 driving pinion g and advancing the rod g1to apply the brake and allow the cam to bring the dies into openposition. On the reverse or return travel of the saddle the rod .Ireturns and tappet j1 engages the end of rod H and forces it backwardagain rotating pinion gG thus retreating rod g1 and releasing brake. Therod II is driven against its spring by the tappet jl and is pushedthrough bearing G until the notched part it* is engaged by the catch h5thus retaining the spring in tension.

It will be seen that the tappet j1 prevents the screwing machine saddlefrom being withdrawn more than a certain distance from the die head anddies, so that by putting the work to be screwed into the vice, so thatit just comes flush with the front of the dies, any desired length ofthread within the range of the mechanism may be screwed over and overagain. Moreover the dies are re-set to size automatically without anymovement on the part of the operator being necessary other thanwithdrawing the screwing machine saddle. Y l

In this device the opening or releasing of the dies is entirelymechanical e'. e. it is performed by the engine or motor or other powerwhich is driving the machine, and is not done by a spring or springs.One spring only is used7 and that is to turn the cam back to the set orclosed position after t-he dies have been opened or released, so thatthis spring is only subject to the lightest of work. Y

The overhang of the die head from the main bearing of the machine isvery greatly reduced by the before mentioned device, which is obviouslya great advantage, as the bed of the screwing machine can be shortenedaccordingly, or if the length of the bed remains the same the eXtraspace available allows the saddle or vice increased travel and soincreases the capacity ofthe machine.

Left hand threads can be screwed by removing the right hand cam andsubstituting one of the opposite hand, which operation can be carriedout in a few minutes. No other alteration or addition to the machine isnecessary except of course the left hand screwing dies.

In this device the opening or releasing of the dies is reallyinstantaneous, no time being lost through t-he operation of specialreleasing cams or trip gears.

It may be desirable to provide a catch over the cam pin o3 to avoid anypossibility of the dies running back whenV the machine is at work onheavy screwing. Such a catch is shown at Figs. 7 and 8 in which abracket K is provided with a boss in which a spring plunger 701 isarranged. The plunger is provided wjith inclined faces 7a2 7c3 forengaging in a shaped notch in the cam pin. When the dies are closed andscrewing the plunger engages the pin and holds it in the end of the slotremote from the fixed peg '62. lVhen the brake is applied to the cam andthe die head overtakes it the plunger is carried over the pin so thatthe dies may open.

What we claim and desire to secure by Letters Patent is l. A die headconstruction :tor screw machines comprising in combination, a rotary diehead provided with an adjustable stop device having a slot therein, diesradially movable in said head toward and away from the work, a camelement provided with scroll cam portions for operating said dies andhaving a pin projecting into said device slot, a spring connected withsaid cam element and device for shifting the dies to a working position,and a brake device acting on the cam element to cause suiicientdifferential movement between the cam and head so as to retract the diesfrom the work.

2. A die head construction for screw machines comprising in combination,a rotary die head, dies radially movable thereon t0- ward and away fromthe work, a cam element provided with scroll cam portions for shiftingsaid dies, a spring connected with said cam and head to normally advancethe dies toward the work, a device adjustably mounted on the head forconnection of one end of the spring thereto, means anchoring saiddevi-ce in adjusted position, and a brake device acting on the cam tocause sutcient relative movement between the cam and head to retract thedies from the work.

3. A die head construction for screw ma- Chines comprising incombination, a rotary die head, dies radially movable toward and awayfrom the work, an element provided with means for shifting the dies, aspring connected with said element and head to normally advance the diestoward the work, said head having a segmental slot therein, a block insaid slot forming a connection for one end of said spring to said head,means for anchoring said block in said slot, and a brake device actingon said element to cause suiiicient relative movement between theelement and head to retract the dies from the work.

4. A die head construction for screw machines comprising in combination,a rotary die head, dies radially movable therein toward and away fromthe work, a cam element provided with scroll cam portions for shiftingsaid dies, a spring connecting said cam and head to normally cause thedies to advance toward the work, a catch device for retaining the partsin such working position, and a brake device acting on the cam to causesuiiicient relative movement between the cam and head to retract thedies from the work.

5. A die head construction for screw machines comprising in combination,a rotary die head, dies radially movable toward and away from the work,a cam element provided with scroll cam portions for shifting said dies,a spring connecting said cam and head to normally cause the dies toadvance toward the work, a releasable catch for holding the parts insuch working position, and a brake device for causing sufficientrelative movement between the cam and head to retract the dies from thework.

6. A die head construction for screw machines comprising in combination,a rotary die head provided with a slotted portion, an adjustable stopdevice in such slotted portion and provided with a slot therein, diesradially movable in said head toward and away from the work, a camelement provided with scroll cam portions for shifting said dies andhaving a pin projecting into .the slot in said stop device, a springconnected with the pin of said cam element and said stop device forshifting the dies toward a working position, and a brake mechanism forcausing suiicient relative movement of the cam element and head toretract the dies Jfrom the work.

7. A die head construction comprising in combination, a rotary die headprovided with an adjustable stop and spring holding device, diesradially movable on said head, a cam-like element connected with saiddies for shifting the same and provided with a projection engaging saidstop device, a spring connected with said stop device and said camelement to normally cause the dies to advance toward the work, andbraking means for causing suiiicient relative movement between the headand cam element to retract the dies from the work.

In testimony wherof we aiiiX our signatures in presence of twowitnesses.

THOMAS CHATWIN. THOMAS PHILIP CHATWIN. JAMES VIRTUE.

Witnesses:

F. GILBERT BRETTELL, J. BEAUMONT PERCIVAL.

Copies of this patent may be obtained for ve cents each, by addressingthe Commissioner of Patents, Washington, D. C.

